A magnetoresistive random access memory (MRAM) is known as one kind of magnetic memory. The magnetoresistive random access memory stores data by using a change in the resistance of a magnetoresistive effect element caused by a change in the relation of the magnetization directions of two ferromagnetic layers constituting the magnetoresistive effect element.
A memory cell of the magnetoresistive random access memory includes the magnetoresistive effect element and a field effect transistor (hereinafter referred to as a select transistor). A plurality of ferromagnetic layers and a nonmagnetic layer are stacked in the magnetoresistive effect element. The select transistor functions as a selecting switch. The magnetoresistive effect element includes the ferromagnetic layer which is invariable in magnetization direction (hereinafter referred to as a magnetization invariable layer or reference layer), the ferromagnetic layer which is variable in magnetization direction (hereinafter referred to as a magnetization free layer or storage layer), and the nonmagnetic layer intervening between these ferromagnetic layers. Data is written by changing the magnetization direction of the magnetization free layer.
In order to improve element characteristics, magnetoresistive effect elements using new techniques are under development. For example, Jpn. Pat. Appln. KOKAI Publication No. 2009-80878 has disclosed a magnetoresistive effect element (magnetic recording head) utilizing a high-frequency assist effect.